Method of generating bevel gears



Oct. 2, 192:;

METHOD OF GENERATING BEVEL GEARS E; WELDHABER Filed Feb. 28, 1927 2 Sheets-Sheet 1 IIIHHI Ila ! llllllH INVENTOR est Wildflabm ATTORNE Patented Get. 2, 192a,

iRooH s'rER, NEW YORK, A CORPORATION- OF NEW YORK." f

METHOD on GENERATING, B EL GEARS.

' Application filed.Fehruary 2s, 1927. Seria1lNo. 171, 10. 1

- The present invention relatesto a method of producing gears and particularly to a method of producing bevel gears havin longitudinally curved teeth. r I r The primary object of this invention is to provide a simple and practical method for producing bevel ,gear pairs, in which the side toothsurfaces of each" member of the pair may be out two sides simultaneously, in

10 such manner that the mating gears will mesh o without bias bearing. i, a A further ,object'of this lIIVGDtIOII is to provide a method for cutting bevel gears,

in which the toothed surface of each member of the pair may be out two sides simultaneouslyvin such manner that the teeth taper inIdepth alongtheirlength'in proportion to i the taper of the gear itself, with the tooth bottoms runningg.,substantiallyVto the gear apexes, so that gears may be produced in a rapid operation whicharejust as strong as gears whose tooth surfaces are cut one-side atatime. z, H

Afurthetbbject ,of this invention is to '28 provide a methodfof cutting bevel gears two sides simultaneously which, willv permit of employing existing machinery in cutting 7 both members of a pain; v

Other-objects of this invention Wlll be apparent hereinafter from-the specification.

and from the recital of the appended claims. In the accompanying drawings, I have illustrated the preferred method of practising this invention in producing a bevel gear pair having longitudinallycurved teeth. o It will be understood, however, that the invention capable of further modification withappended claims.

40 1n the drawingszi' r i Figures 1 and Qare a plan iew and side elevation, respectively, illustratingdiagrammatically the preferred -method of producing the larger member of; a longitudinally curved tooth bevel gear pair accordingto this invention; r 1

in its scopeand within the limits of the V l Figure 3" isasectional viewoof the cutter i I i .gears and particularly in cuttin-gthe larger or tool used in cutting this member; r

Figures 4c and 5 area plan view and side elevation, respectively, illustrating diagranr maticallythe preferred method of producing a pinion or smaller memberto mate with the gear out according to the method illus trated in Figures 1 and 2; and, Y

' Figuretois a sectionalview of thecutter used 1n producing the pinion. Y While the present invention maybe ap- ERNEsrwILnHABER, 'oFB RooKIJYN, NEW YORK, ASSIGNOR ToGLEAsonJwonns, 0F

plied to the production of straight tooth 1 bevel; gears, it is particularly applicable to the manufacture of curved tooth or spiral bevel gears and it is in connection with the latter type of gear that theinvention is herein-described, v s

A principal purposei of t is invention is to permit of thecutting of both members of the bevel gear pair two sides simultaneously vwithout biasbearing and with the requisite tooth strength, upon existing machinery.

To this end, the gear orlarger member of the pair is preferably cut in a generating operation inwhich the tool and blank are rolled. relatively to each other, as through gear,-represented 'by the vtool, andnthe pinion or s'mallermember of the pair, is produced ma generating operation, in which thejtoojl "the pitch, surface of the blank were rolling upon the pitchsurfaceof a nominal crown represents a basic gearhaving conical top,

pitch, and rootsurfaces andya pitch cone angle different from the pitch cone angle of the gear withiwhich the pinion isto mesh;

The gear or, larger member ofthe pair can,

accordingly be produced upon the standard.

Gleason spiral bevel gear generator 'the structure of which is described,generallyyin the patentto Gleason, et al.,-No,* 1,203,608,

Novemberf.7,,,1916.1 The gear may be cut, moreover, with astraight sided .orxconical rotary annular face 'mill', according to. the usual method employed in cutting bevel gears spread blade that is, two sides simultaneously.

The pinion tion No. 77,310,;filed December 23, 1925.- A,

vmay be out ,upona machine such'as descrlbedm my copendmg applica special cutter is required for cutting dthe Y pinion. It" will have finish cutting ,edges which are slightly, convex. s The gear or larger memberof the pairis produced in a manner similarlto that employed, at the present time, in cutting bevel f member of a bevel gear pair spread blade ,y

tool employed will be preferably a rotary "ting of straight profile. The gear blank tobe out is shown at 12. For gener- '1 ating the tooth profiles of the blank, the tool 10 is rotated in engagement-with the blank and silliultaneously the tool and. blank are moved relativelyto each other, as though the i blank were rolling with a nominal crown gear 13 represented by: the tool, having a plane. top surface 14 and a conical pitch surface 15,. In this generating operation, the tool 10 is rotated on its axis '16 and;

preferably, the blank 12 is rotated on its axis 17, while simultaneously an additional relative movement is imparted between the tool 10- and blank 12 about an axis 18, repre: senting the axis of the'nominal crown gear 13, which axis 18 intersects the axis 17 of the blank in the blank'apex 19.

The tool- 10 is provided-with cutting edges for finish cutting adjacent side tooth faces of a the-blank,qso that, asthe tool rotates in enturn adjustably mounted upon the cradle 24.

gagement with the blank two adjacent side tooth surfaces of the blank are cut simultaneously. To this end, each of the cutting blades 11 of the tool may be provided with two finish cutting edges, or alternateblades maybeprovided with finish cutting edges for cutting the adjacent side tooth faces of theblank. Each of the blades of Mietool 10 shownihave two finish cutting e cs 11 and 11 of straight profile.

s stated, the

ear, or larger member "of apair of longitu inally curved tooth bevel gears produced according to this invention, ma becut upon a'Gleason spiralbevel gear generator. This type of machine is illus- 'trated diagrammatically in Figures 1 and 2.

'Ihe cutter head 10 is mounted upon aspindle 20' which is journaled in a support 21 that is adjustable upon an upright 22,;which' is in The cradle 24 isoscillatably mounted in the thoughthe blank were rolling with the basic gear 13. After two adjacent tooth sides, of the blank have been cut, the 'tool and blank-are withdrawnrelativelyto each other and the blank indexed. The tool and blank aret'hen returned into engagement and the peration proceeds as before until the blank "has been completed. It is customary to cut the gear or larger member of the pair spread blade, ortwo sides simultaneously, in a mannersimilar to that described, butwhen the pinion or mating'gear is out in a similar way, difi'iculty is experienced in eliminating bias bearing orr a toothsurface contactv which extends straight.

diagonally across the faces of the teeth when the mating gears are run together- It has been found that bias could be eliminated on both sides of the tooth surfaces simultaneously, if a somewhat large modification of the tooth profiles were permissible or practical. A large modification of the tooth profiles, such-as would be accomplished by rolling the pinion on a tapergear instead of a crown gear for generation, would, however, produce tooth surfaces which were too much curved on both sides of the teeth and the tooth bearing would then be too narrow. I

have discovered, however, that biasbearmg may be ehminated by generating't-he pinion conjugate to a tapered" gean which as a predetermined pitclrconeangle and compensating for the resulting "modifica tion of thetooth profile by providing the cutter blades with convex profiles'insteado-f gear used in generatlng the pinion-will be smaller than and usually in the neighbor'- hood of 82. The cutting edge of the tool needonly be slightlyconvex; For instance, for a rotary annular face mill of 9lcutter The pitch cone angle ofthebasic diameter, the cutter 30 (Fig. 6)" employed in producing the pinion will usually havecutting blades 31, the profiles of whose finish cutting edges. are-curved on a radius of "approximatelyw12. 1

in The preferred methodof producing the pinion isillustrated diagrammatically in Figs. 4 to 6. Thecutter 30 emp1oyed is a rotary annular face .mill' provided with a plurality, of cutting blades 31; The finish cutting edges 31 and 31 of these blades will be of convex profile asstated; Each blade may have two finish ci'ltting'edges, oralternate blades maybe provided with finish cutting edges for finish cutting adjacent tooth faces of the blank." Inboth Figures 3 and 6, the tool shown is provided with. blades so fashioned as to have, each of them, two finish cutting edges. v w I provided with a front rake, usually about 15, so as to give them a good cutting action.

In the generation of the pinion,;the cutter 30 represents a basic gear 34' which hasconical top, pitch and root surfaces, respectively,

These blades are preferably 35, 36. and The tool 30 is rotated in engagement with the pinion blank 38while simultaneously the tool and blank are rolled together as' though 'the blank were rolling with the taper basic gear'3 il Preferably, this rolling motion comprises a rotationof the blank 38 upon its axis 39 and a simultaneous relative movement between the tool and blank about an axis 40 representing the axis of the basic gear-.34 and intersecting the blank axis 39 in the blank apex 41.

The pinion can be readily cut upon a machine of the type described in my application No.77,310, above referred to, since in such a machine the tool'can be adjusted angularly' about two axes at right angles to eachtother and positioned so as to represent.

altooth surface. or :tooth surfaces of a basic gear, such as the gear 34, .whose' pitch cone The upright 45is in turnangularly adjust able upon -'the ,cradlei47, being pivotable thereon about a studi l8v The two angular adjustments in addition to the usual acljustinents provided upon longitudinally i vto the pitch surface of the crown gear or curved .tooth bevel gear cutting,,machines,

depth and, with toothbottoins which run permit of. adjusting; the cutter .30 about either or bothaxes .loand 48 to represent- 7 "lines'of" the crown gear orbasic gear, due

a=basicgear34 ofthetypedescribed. V

During generation, the cutter 30 rotates inengagemerit-withthe blank '38, cutting out two adjacent tooth surfaces otthe blank simultaneously, the blank rotates on its axis 39 and simultaneously the cradle ismoved onits axis which represents the axis ofthe basic gear 3a., After two toothisurrtaces of the,blankhavegbeen cut,- the, tool and blank are withdrawn relatively to eachother and the blank indexed; The tool and blank are then returned into engagement and two other tooth surfaces of the blank are then enerated. The operation then proceeds I as before until-the blank has been vcompleted.

When a pair of mating gears have been produced in thermanner. described, they will mesh together without bias bearing, their apexes will coincide, as usual in bevel gears, and they will transmit true uniforni motion. Each gearn ay be; cut with teeth of tapering to their 'apezres thatj is, lie on conical surfaces the apexes ofwhich coincide with .or substantially coincide with the pitch cone apexesvof theblank. In this. way, gears. of

satisfactory tooth bearing can be produced in a rapidsoperation and with" teethijust as strongas gears cut one side at a ti 1ne Nhile in both instances, I have shown the tool ,inounted upon the cradle, It Wlll be unglerstood that the same generating v motion can beobtained by mounting the" blank upon the, cradle and applying simply a cutting motionto the tool. It will be under;- stood, also, that if desired the blanlcmight beheldstationary during the cut and all offlthe generating The radii oi the transverse or cutting-pro files of the tool to be em )loyed in cutting the pinion, the form oft e basic gear upon which the pinion is to be rolled, and the pressure angles oflthe cutting blades of the the pinion blank.

otion applied to pinion cutteriwhich arerequired to obtain caring for a suitable length of the tooth face, can be determined ELSIfOllOWSQ Let (-1)) bethe pitch cone angle; of

the basic gearupon which'the pinion is to,

be rolled for generation, cl be the, dedendum i 9' be the average cutter radius, thatis, the

distance from the center oraxis about which the tool rotates vto the mean point of contact and let 8 be a pitch line element of the b'lank'" l Now the inclination of the tooth normal basic gear't'rom which'the pi'nion' isgener-w P ated changes at various points 'on'the pitch to the inclination of'thecutter; axis to the basic .gear axis. This is true; of the pinion also; The tooth normal has one inclination at the'mean point of contact; between basic and pinion and anotherinclination at same'other point inthe pitch lines, The in v creinent or decrement (a) 'of'the tooth nor mal can be expressed as follows 1 i s a; =Fcos a-d-cos h--I V cosa r "s sin h l cos h-cos av tan D],

where a is the inclination of the tooth; normal at themea'n contact point orthe pressure angle; Inasmuch as we c'onsider' tl1e pitch lines,-thej pressure angle will be the same. for the crown gear or basic gearfand The e nation j st given can be simplified to: g n

i iE 'diSjm been] on the ear or other-member of "the air m V i p I 7 the increase in pressure angle for the same point when it becomes a point of contact between gear and pinion is:

where d is the dedendum angle pinion and D is,'as will be pointed out be low, the dedendum angle ot thegearbp 1' 'The'increment of pressure angle, a must evidently be the same on; both members of the pair,'h ence;. T

. Now where the gear I or larger. member of I e i lQli I iris out upon a] standard Gleason can be, determined; as follows:

In order to be able to cut the tooth boti towards, in line with, the blank apex,

. Q gear 34,

the spiral an'gle'k, the cone distance'A and the cutter radius a" must have the same interrelation asin the case of bevel gears pro-.

duced with a spherical cutter, namel-yz (1 -sinh) ita'n a -D cos k,

r p 1r Where D is'the'aVerage dedend-um for one dia'metrical pitch. D usuall equals 1.2.

V The radiusof curvature of' the normal tooth profile 'ofa basic gear, such as the whose pitch cone angle is 90-D 1s: V V

. A sin a cos h tan D' if the true crown gear has a straight normal profile. The pinion cutter is, therefore, ro-

Yi'ded with; a cutting profileof this ra ius, when full profile match between the tooth surfaces of the gear and pinion is desired.

'While for practical reasons, it is preferable to use a straight sided cutter on the gear, the profile curvature might be split 7: between the gear-"and pinion cutters.

-tools which move in arcuate paths.

instance, the profiles of the cutting edges ofthe two cutters "might be made of equal curvature, in which case the profile radius would be twice the above amount or:

. i Asin a "cos' I tan D Any desired lengthwise mismatch of the tooth surfaces of the gear and pinion produoed according to this invention can be obtained by varving the inclination of the outside and'inside cutting edges of the tool and setting the cutter onthe generator in corres ondence withsuch inclination.

M ile I have deemed it preferable to cut both members of a pair of curved tooth bevel gears accordingto this'invention with rotary annular face mills, it is also possible to cut either'or bothmembers with planing The present invention may be applied to grindgear generator, as is preferable, the

teem

ing and lapping and isx-not confined; to: the i production of gears; with milling or i planing operations.

In general, while Ihave describedzmy. in

} vention with reference. to a particular embodiment, it will be understood the; inlvenftionis capable of furthermodificationwithin the limits of the disclosure and the. scope of the appended claims and that thisapipl-ication is intended to cover. any variations,-uses or adaptations. in my. invention, following, in general, thevprinciples, ofwthe invention and including such-departures from the; present disclosure as come: within known or customary practise in the. gear! art and asniay be applied to the essential features hereinbefore set forth andas fallwith in: the limits of the accompanying claims.

' Having thus described my invention,what Iclaimis:

. 1. A method of producing a bevel. gear which consists in cutting each ofit'si side tooth surfaces by movin 'a tool having acutting edge of convex pro le, across the'faceof a tapered gear blank while 'imparting: a relative rolling movement between the tool and blank as though the blankwere rolling with a basic ear having conical top,-p itch, and root sur aces, andapit'ch cone angle different from the pitch coneangle of its mating gear. .3

2. The method ofproducin'g a bevelgear which consists in cutting each' 'of its "side tooth surfaces by moving a tool,having a cutting edge of convex'pi ofile, acurved path across the face of a tapre'd'gear blank,

vwhile imparting a" relativerolling movement-between the to'ol and-blank as? though the blank wererolli ng with" a basic gear having conical top, pitch, and root surfaces; and apitoh cone angle different from tlie' pitch Y cone angle of its matingjgearr I 3: The method of5pr0diicin'g abevel'gear which consists in cutting-eacliofits "side toothg'surfaces with a rotary annular face mill,-h aving a plurality ofgci'itting edges of convex profile, by rotating said toolin engagement with a tapered gear blank while imparting, a'*relative= rolling moven'uent betweenthe tooland blank'as though the blank were rolling with a basic gear having conical top, pitch, and root surfaces, and apitch cone angle difl'erent. from. the its mating gear. V V

4. The'method of producing a bevel gear its 7 120' pitch cone angle of which'consistsin finish cutting its side tooth surfaces two sides simultaneously, by moving a pair of cutting edges, each of 'which' is of convex profile, across the face-ofia tapered gear blank while imparting-1a: relative rolling movement between the cutting edges and *blank as'though the blank were rolling w-ith a basic gear having a conical pitch surface whose pitch cone angle is different from the pitch coneangleof amating. gear-J; v V

5. Th'e 'method of producing a. bevel gear which consists in finishcutting its side'tooth surfacestwo sides simultaneously by moving apair of cutting'edges, each of which is of convex profile, across theface of a tapered gear blank while imparting a relativerolling movementbetween said cutt ng edges and.

blank asthough the blankwere rolling with abasic gear having conical top, .pitch, and

root surfaces and a-p itch cone angle different from the pitch [coneangleof them-ate. gear.

6. The method of. producinga bevel gear whichconsists in finish cutting its side tooth surfaces two sides simultaneously by moving apair of cutting edges, each .of which is of convex profile, in separate concentrically curvedpaths across'the face f a tapered.

gear blank while imparting. a relative rolling movement between the cutting edges and blank as though the blank wererollingwith" a basic gear, having a conical pitch surface whose pitch coneangleis different'from the pitch cone' angle of mating gear. 1 t

7 .7 The method of producing a bevel gear I which consists infinisheuttingits side tooth surfaces two sides simultaneously with a rotary annularface mill, ,pIOYldQCl NVlth cutting edges, each of'which is of convex, profile,

' adapted to finish cut adjacent side tooth-faces of a blank, by rotatingsaid toolin engagement with a-tapered gear blank, while imparting a relative-rolling movement between the tooland blank as though the blankwere riolling with a basic' gear having agconical pitchsurface whosefpitch coneangle is different from the pitch cone angle of a mating v root 'isur-fa'cesanda pitch eone angle dif- 'ferentfrom the pitch -eone angle ofj'a mate s e 1 1 m- 9.,The method ofproducing a bevel; gear which consists in ffinish cutting its side tooth surfaces 'twoisides simultaneously 'with a rotary annular-face millf, provided with cuttingedges, each-of which is of convex profile,-

adapted to fii1ish-cut-adjaeent sidetooth,

faces; of a blank; by rotatingsaidtool in engagementwithQa tapered gear blank while imaprt'ing Ya relative rolling movement between the toolgand blank {as though theblank were-rollingwith a basic gear having, conical top,:,p itch,=and root surfaces, and-agpitch cone angle. differentfrom the pitch cone angle of, a mate gear. 5 lQQThe -m thod of bevelgears which consists in cutting theside tooth surfaces of onelmeinber, ofthe ,pair by moving a cutting edge of straight profile aroducin a air, of

across the face of a: tapered gear blank while imparting afrelat'ive rollingmovement between the tool-and blank as though the/ 7 blank were rolling on a basic gear having a planetop surface and a conical pitch. sur face, and in euttingzthe side tooth surfaces 3 of the other member by moving a' cutting edge of eonvexpprofile across the face of a tapered gear blank-while imparting a rela v 'tive rolling movement between said latter cuttlng edge and blank as though the blank were .rollingwith a basic gear hav'ingconical top, pitch and root surfaces,

,.11. The method offroduc1ng avpair of bevel-gears, which consists cuttingthe side tooth surfaces ofone me nber by-moving a cutting edge of straightv profile across the face of a tapered gear blank while impar't 'ing arelative rolling movementbetween the tool and blank asa though the blank were rolling on a basic gear having alplane top surfaceand a conical pitch surface, and'in cutting the side tooth surfaces the other memberby mov ng a euttlng edgeiof convex profile" across the face: of a, tapered [gear blank while imparting {a relative rolling movement between said lattercutting edge andhlank as though the blank were rolling with "a basic gear having conical top, pitch, 19

and root surfaces and a pitch coneangle 1 difierent from the pitch cone angle of i v ,mate gear y ,v 'i l2. The met 0d of "cutting a' pair of bevel gears-which cons sts in cuttingtheside tooth v surfaces of one member of the pair two-sides 7 simultaneously. by: moving a pair of cutting edges of, straight profile across the face-of a tapered gear blank while imparting a relative rolling; movementbetween the cutting edges and blank as though on a basic r-gear 'havmg a plane top surface the side-tooth surfaces ofthe'other. member of the pair twp sides simultaneouslyby m'ov ing a pair of cutting edges of convex profile acrosstheface of a tapered gear blank wh le 1 1g.) ithe blank were. rolling j and a conical pitch surface, and in cutting r imparting a relative rolling movement be tween-'theglatter cutting edges and blank-as though' the blank were rollingwith a basic gear having conical top, pitch, and root surfaces. j

13.- The? method of cuttingqa gears which. consists in euttingthe s de tooth surfaces of one member ofthe pair two sides simultaneously by moving ajpgalr edges of straight profile across the face of a tapered gear; blank while imparting a relative -rolling movement. between the. cutting ges an ank as tho gh'r jb of cutting Y rolling m1 ma ic "gear having a "p'lene top surface and a conical pitch surface, ier'idfin 'dtittitig the side tooth surfaces of the other member of the pair two 'sidessimulteiieously b'y'moving a -p a r of cuttin edges of convex p'ro'fi1e, 'ecross the face a tapered gear bl'unk while imparting re relatlve rolling nibvemnt between the latter cutting edges i and blank asthough theblank were rolling with a. ear having conical top, tpitch end [root sur aces-and a pitch cone *angle' flifl'ei-ent from the pitch cone angleof the mate'an' 14. he method of "cutti ng a. pair-10f "tfipi'et'larswhich consi'sts in cutting the e 1 h el t' q n m mb Ti li pair by moving "emitting edge of streight profile in a 'curved peth acrbss the {face "of a tapered gear blank whilerot'ating are blank Lexis and 'simulteneously ii np'arting an iitltlitiona'l relative movement between the r cuttin edgeendblenk about an axis parallel to he axis about which the 't'oolmove's, and in "cutting the side 'tooth surfaces of the 'dther "ihember of the fpair by moving 'a I cutedge of convex profi'le in a curved path kcrossthe face ofatapered gearblenkwhile rotating the blankon its axis and simultanethe 'hlenk on its axis andeiinulteneously im- 7 mem er mm were re blink about an axis inclined to thea S tooth surfaces of one memberdfthe pair 7 bymoving aicutting' edge'ofi'st'raight'profile il'r'a cal-ted "pa'th across the face' of a tapered geanblank while rotating the blarik'onuits skis anti Simultaneously imparting an edditiondl relative movement between thetool intlbla'nk about an axis which intersects the lihtnk aztis its a) ex and is parellelto the his elbout'which t e tool moves; and incutting the side tooth surfaces or the other Fair by nio ving a cutting edge ofconvex-profi e ina curved path ecrossthe Tithe 'df reaper-ed g'ealrhlank while'rotating pertin'gan etlditibntil reletiv'e movement be,- tween theletter cutting e'tlgeand blenk about dniiiiis which intersects-the blank axis in its fexan'd whlh iis inclifietl to the axis about fichthe letter'tiitil'mdves. i .16. "iiiethod of f cutting a pair of tageretl gears which cor'rsistsin cutting-the i' e tooth surfaces ofone memberofthe pair tyvo sides simultaneously by moving a "pair ofieuttih g ofj' ttraight profilein sepaldlfe 'cbheehtrlcfilly I curved p a'iths heroes the iiicedfatepe'rd geeflblank while imparting areletive rolling movementbetween'the cutting e'dfiesend blank as though the blank M V ingw ith aba'sic 'gear'having "a'plane top surfe'ce ande' conical pitch surface,- and in'uttin the sideztoot surfaces of the other 7 leases-4 member (if the pe'irtwoeiaes iiniflcaneusly by moving a pair of cutting edgsercdnvex profil in separate concentrically eur'vea paths across the face of a tapered ge'efibla'nk while imparting a, relative rolling movement between the latter cutting edges "and 'bla'ri'k as though theblank were rolling "with a basic gear having conical top, pitch and root surfaces."

17. The method of cuttinga pair of tapered geerswhich consistsin cutting'the fsi'cle tooth surfaces of one member of rthe pai'r by"movin'g acutting edge of Fstra'ight profile in a curved 'path "across the face 6f a teperelgearblenkwhileimparti a relative rolling movement between the cutting eager 'and blank as though the"blank were rolling and a conical pitchsurfac'e iin tl, in cutting the .other member of the pair by m vinge path across the face of'a tapered geel'r blaiik While imparting "a relative rolling mov ment between the latter cutting edge and blank as though the blank were roning with a basic gear having conical top, pitch und root surfaces.

18. The inethotlof cutting e 'pa'ir "02Ev tapered gears, which consists in -cutt-ing the side tooth surfaces of one 'mein'be'r of the profile, rotaiting saititool in engagementwith' say tapered gear lilaiik while rotetilig the "blank on its eiiis end simultaneouslyimparting an additionel relative movement between the"too'l and blank about an ex'is cutting the silietooth s' urface's of the other member of the pair with a, rotary anrilllar ace milhheving a plurality of ciitting edges of convex profile-b rotating; the letter weal I in engagement with-"a tampered gear 'bl'a-nk while teeming the "blank on iitsfexifs' sihd f'si- ,niulteneously impel-ting an additionel r-elm tive j movement between the latter tool and blankaboutanlaxisinclin'ed tb the-exisubout which thelatte'rtool rotates; 1

l9.'Th'e 'inethod of ciitting 11" pair of tapered gears which consists in cutting the side teeth surfaces "of "one *member' df "the pair with a rotary Tannuhi'r rate mill, hat-v ing a plurality of cutting edges of straight profile; by rotating said "tool m engagement with a tapered gear bla'ilk while rotating the blankOn its axis anti simultaneously his 7 I no imparting sin edditio'n'al rel ati'v'e movement between "the tool and the blankaboutya-n axiswhich intersects -the ble'rik a Xis in apex and is parallel to theilotaryMantis of the 'toohend in c'utti-ng the' si'det'ooth sun faces of the other ine'mbe'rgof the pair' with a rotary annular fece inill, having a plur ality of cutting ledges offc'onvex -=p'rofi'l'e,' by rotating; the latter tool in engagement with a tapered 'gear blank while rotating the blank on its axis and simultaneously imparting an additional relative movement between the latter" tool and blank about an.

axis which intersects the blank axis in its apex and is inclined to the axis about which thelatter toolrotates.

The method of cutting a pair of tapered gears which consists in cutting the side tooth surfaces of one member ofthe pair two sides simultaneously with a rotary" annular face mill,having cutting edges of straight profile, 3 adapted to finish out op posite side tooth faces of the blank,by ro-' tating said tool in engagement witha ta--' pered gear blankwhile rotating the blank on its axis and simultaneously impair-ting 1 an additional relative movement between the 'tool and blank about an axis parallel to the axis about which the tool rotates, and in cutting the side tooth surfaces of the other member of the pair with a rotary annular face mill, having finish cutting edges of convex profile adapted to finish cut adjacent side tooth facesof a gear blank, by rotating the latter toolin engagement with 21 tapered gear blank while rotating the blank on its axis and simultaneously imparting an additional relative movement between the latter tapered gears which consists in cutting the side tooth surfaces of one member of the pair with a rotaryannularface mill. hav-I axisabout which the latter tool rotates.

tool and blank aboutan axis inclinedto the 211Th'e method of cutting a pair of mg cutting edges of" straight profile'adapted tofinish cut adjacent side tooth faces "of a tapered gear blank, by rotating thetool' in H engagementwith atapered gear blank while rotating the blank'on'its axis and simul taneously imparting an additional relative movement Joetween the tool and blank about an axis which intersects "the blank axis in. its apex and which ,is parallel to the axis about which the side tooth surfaces of the other member of the pair, with a, rotary annular face mill, having cutting edges of convex profile adapted to finish cut adjacent side tooth faces of a gear blank, by rotating the latter tool in engagement with a tapered gear blank while rotating the blank on its axis andsimultaneously imparting an additional relative movement bet-ween the latter tool and blank about an axis which intersects the blank axis in its apex and is inclined to the axis about which'the latter tool rotates.

22. The method of cutting a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair by movmg a cuttlng edge of straight profile in a curved path across thelface of a tapered gear blank while imparting a relative rolling movement between the cutting edge and blank as thoughthe blank were rolling with tween the latter cuttingedges'and blank as though the blank were rolling with a basic thetool rotates, and in cutting a basic gear having. a plane top surface and a conical pitch surface and in "cutting.

the side tooth surfaces of the other member of the pair bymoving a cutting edge of 'convex profile in'a curved path across the face of a tapered gearblank whileimparting a relative rolling movement between the latter cutting edge and blank as though the blank were rolling with a basic gear having coni-; I

cal, top, pitc h and rootsur'faces and apitc-h cone angle different from the pitch cone.

angle of the mate gear.

23. The method of cutting a pair of bevel: gears] which consists in cutting the side tooth surfaces ofone member of the pairtwo sides 7 simultaneously by moving a pair of cutting edgesof straight profile inseparate concentrically curved paths across the face of a tapered gearblank while imparting a relativerolling movement {between the cutting edges and blank as thoughthe blank were rolling with a basic gear having a plane top surface and a conical pitch surface mun cutting the side tooth surfaces of the other member of the pair two'sidessimultaneously vex profile in concentrically curved paths across the face of a tapered gear blank whileimparting a relativerolling movement be gear having conical top-,pitch-, and'ro'otsur faces and apitch. cone angle different from the pitch cone angle of the mate gear.

24. The method ofproducmga pair of bevel gears "which consists in cutting the side tooth surfaces. of one member of the pair, two sides simultaneously with a rotary annular face mill, provided. with cutting edges ofstr aight profile adapted to{ finishcut ad- .by moving a pair of cutting edges of con= jacentsidetooth faces-of a gear blank byrotating said tool in engagement with a tapered gear blank while imparting a relative rollingmovement between the tool and blank as though the blank were rolling with a basic gear having a plane topvsurface and a conical pitch surface, and in cutting the side tooth surfaces of theother member of the pair .two sides simultaneously with a rotary annular face mill, provided with cut--.

the pitch cone a v ting edges of convex profile adapted to fin- [sh cut adjacent side tooth faces of a gear j adapted to finish cut adjacentside tooth toohaxia, v

faeesof a gear blank, one member of the paihbeillg cut in a generating operation in- 'which' the tool is; rotated in engagement with a "tapered gear blank while theblank is, rotated on its ,axis, and simultaneously an additional relative amovementsis imparted between the tool and blank about an axis interfiflctmg the blank axis and parallel to the tool 'axis,3the other member of the pair being cut in a generating'operation; in which the toolis rotated in engagement withatapered.

while the blank is ,mtated on itfi; aegis; and simultaneously an additional relative movement is imparted ,between the blank. about an axis intersecting the axis and ,angula'rly inclined to the 7 2a., The mean of, treating a ar f "bevel-gears which consist's incutting the sid'eftoothrsurfaces .of both members of the, pair twosides simultaneously, by moving a pair of cutting edges ingseparate concentrmally'curved paths across the face of the gearv blank," one member of the pair being cut in a generating operation, in which durthe cutting movement .of the cutting edges, theblankais rotated on its axis and simultaneously an additional relative move- J mantis imparted betweenthe cutting edges" andblank aboutan axis whichintersects the. blank axis in its apex and is parallel to the. axis, about, which vthe cutting. edges move,

and the other memberfpfythe pair being cut ina generating operation in which, during the; cutting movement ,of the cuttin .edges,

the blank is rotated on-its anis an simultaneously ,an additional, relat ve movement isimparted betweenithe cutting edges and a 11-. t -a x n i n elsy profile in kebbnt an axis which intersects. the, blank,

'tool;, having a conical pitch surface 3 r Y a NES WILDH ER -1 clined to the axis about which the cutting edges move.

2 7, The method of producing a pair of: V V 45, g

between the tool and blank in the mannerofa gear rolling with a'basie gear, represented I by the tool,-.having a conical pitch surface.

28. The method of producing a. pair of bevel gears which consistsin cutting theside a tooth surfaces of one-Imember ofvthe pair,

two sides simultaneously with a rotary-an;

nular face mill, having ajplurality'of, cutsv ting edges of straight profile- .adaptednto finish cut adjacent side tooth facesfof a gear blank, by rotating the toolin engagement with a tapered gear blank while impartingv a 7 relative rolling movement between the tool and blank, and in cutting thesidetoothv surfaces of the other member of'the pair twog j sides simultaneously with a rotary annular face mill, having a-plurality of 'finishgcutting edges of convex profile adapted -to,fin- 75c ish cut. adjacent side tooth faces (if-a. gear.

blank, by rotatingssaid tool in engagement With ata'pered gear blank Whileimparting a relative rolling movement between the vtool 'andyblank in the manner of agear rolling witha basic gear, represented by the letter 

